High field spin transitions in Ni2-xCoxScSbO6

Cation-ordered variants of the M2O3 corundum structure are of interest as polar magnets with potential multiferroic properties, e.g. Ni3TeO6 (NTO). We previosuly found that NTO-type solid solutions Ni2-xCoxScSbO6 have a very rich magnetic phase diagram. Ni2ScSbO6 is reported to have an incommensurate [0 ky 0] spin structure but our data for a lightly doped x = 0.025 material indicates a more complex structure. x > 0.1 compositions were found to have a novel series of long-period lock-in [0 0 kz] spin structures with commensurate kz = 1/3n. We propose here to re-examine the magnetic structure of pure Ni2ScSbO6 including field-induced changes which have not be investigated before. We also propose to study the high field NPD of x = 0.05 and 0.1 samples which sit either side of the [0 ky 0]- [0 0 kz] boundary to determine if field can transform one state into the other..